The invention relates to a pipe fitting, especially a control and shut-off valve, comprising a housing and a shut-off element, which preferably is rotatable about an axis, the housing being provided with means, preferably in the form of pipe nipples, for connecting the fitting to a pipeline.
Published German Patent Application No. DE 195 08 789A discloses a shut-off pipe fitting which is configured as a so-called "top-entry" ballcock. The spherically shaped shut-off means is flattened on the top and/or bottom such that it can be introduced into the housing through an opening in the latter. Then the shut-of means is rotated about an axis to the installed position, the said axis being substantially orthogonal to the axis about which the shut-off member can be rotated in the installed position for shutting off and/or releasing the medium flowing through a connected pipeline. This configuration assumes an at least approximately spherical shut-off means and cannot easily be used in cocks having tapered plugs.
Pipe fittings already installed in pipelines, especially welded pipe fittings, require considerable effort in case of repairs or replacement. Complex assembly work, special tools and special jigs are regularly necessary in order to replace or repair worn parts. Known valves whose housings are welded into the pipe have to be removed from the latter and welded back into it after repairs. Furthermore, practice shows again and again that, during installation or during the placement in operation of pipelines, damage is done to the seals, especially by the flushing operations, thereby considerably shortening their life.